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Topic Review (Newest First)

01-14-2006 05:13 PM

onovakind67

No, the vacuum advance cans all advance the timing under increasing vacuum. Some start advancing at lower vacuum than others and some advance farther than others. You need to tailor select a vacuum advance can that suits your engine's needs. You can get a wide range of them at a good auto parts store.

http://www.corvettefaq.com/lars.asp
The following listing (Non-HEI) is as follows: The first two part number listings are the two numbers that are most commonly used in a Chevrolet performance application. The “B1” can is the most versatile and user-friendly unit for a good performance street engine. As you can see, it was selected by GM for use in most high performance engines due to its ideal specs. The “B28” can was used on fuel injected engines and a few select engines that produced very poor vacuum at idle. The advance comes in very quick on this unit – too quick for many performance engines. Do not use this very quick unit unless you have a cam/engine combination that really needs an advance like this. It can be used as a tuning aid for problem engines that do not respond well to other timing combinations, and can be successfully used in applications where direct manifold vacuum is applied to the can (see paragraph and discussion on this above)

After this, the listing is by Echlin part number. The Chevrolet applications are listed first by application, followed by a complete listing of all of the units used on any GM product (all GM units are interchangeable, so you can use a Cadillac or GMC Truck unit on your Vette, if that’s what you want to do).

it has a mild cam, headers, and this intake ...but other than that the motor is internally stock. i do not have anything that measures the vacuum so i m not sure what it is or what it should be. i am guessing that a stock distributer can works the opposite way of the advance can you suggest?

01-14-2006 07:34 AM

onovakind67

Is this a stock engine? What's the manifold vacuum at idle? How much vacuum does it take to run the can? You want to select a can that is all in at idle then hook it to manifold vacuum. If you need to limit the vacuum advance, you can get limiters from guys like this:

so here is the deal fellas. I have been building a 54 chevy 210. I put in a rebuilt 283 with a stock points distributor. I have an edelbrock three deuce intake that was modified ages ago by someone running a 283 in a ford roadster(the guy i bought it from) to take three strombergs instead of three rochesters. So i am running it the same way that he was, running the 2 outside carbs with the center carb blocked off. here is my issue, if you haven t already guessed it. the old 97s have no venturi vacuum, the only vacuum port that i am aware of is on the manifold between the first and center carb...because it is compeltely below the carbs it seems that this isnt a ported vacuum but rather a constant vacuum and would in fact have to be a constant vacuum and would advance the distributor at idle. i am working on digging up the fittings to confirm this...but if this is the case i am looking for suggestions. basically i am looking to find out how to run the vacuum advance on this set up. when i recieved this manifold it the vacuum port was blocked off with what appears to be a compression fitting...oddly enough...as a pipe thread will not fit in it... anyway my point in it being blocked off makes me wonder if he ran a magneto...not that i know anything about mags...but i think they do without a vacuum advance. this is my first car and have learned a lot going along...this maybe something i am starting to understand a little too late. doc vette...hook a brother up
thanks ryan